In this paper possibility to apply a product of poly(ethylene terephthalate) (PET) degradation with triethanolamine as (TEA) water-thinnable hardener is presented. This hardener which contains not only hydrophilic groups and tertiary atoms of nitrogen but also aromatic rings, shows simultaneous affinity for epoxy resins; this permits easy emulsification of epoxy resins with water. Paints on epoxy resins and hardener PET/TEA bases (compositions shown in Table 1) were hardened at 90°C.